Process for obtaining deuterium from hydrogen-containing components and the production of heavy water therefrom

ABSTRACT

The deuterium naturally present in the chemical compounds is transferred to hydrogen having less than normal deuterium content after which the deuterium is recovered from the hydrogen and the recovered deuterium can be oxidized to form deuterium oxide or heavy water.

ZeYQ'fielli? United States Patent [1 1 [111 3,789,112 Pachaly Jan. 29,1974 [54] PROCESS FOR OBTAINING DEUTERIUM 2,908,554 10/1959 Hoogschagen23/204 R FROM HYDROGEN CONTAINING v 2,690,381 9/1954 Taylor 23/212 RCOMPONENTS AND THE PRODUCTION OF HEAVY WATER THEREFROM PrimaryExaminer-Oscar R. Vertiz [75] Inventor: Robert W. Pachaly, Pittsburgh,Pa. Assistant Examiner-Hoke S. Miller [73] Assigneez Gulf Research &Development Attorney, Agent, or Fir mMeyer Neishloss; Thomas CompanyPittsburgh, Pa O. Ryder; Deane E. Keith [22] Filed: Oct. 28, 1970 [21]Appl. No.: 84,578

[57] ABSTRACT [52] U.S. Cl. 423/580, 423/648 The deuterium naturallypresent in the chemical com- [Sl] Int. Cl. ..C01b 5/02, COlb 4/00 poundsis transferred to hydrogen having less than [58] Field of Search23/204C, 204 P, 204 R, 212 R, normal deuterium content after which thedeuterium v I 3/2 423/580, 48 is recovered from the hydrogen and therecovered deuten'um can be oxidized to form deuterium oxide or [56]References Cited heavy water.

UNITED STATES PATENTS 2,787,526 4/1957 Spevack 23/204 R 14 Claims, 2Drawing Figures H29 /0Fpm #0 H 40 /58 xFRACf/O/VATOA #24/0 f /54(auteur/0N 52 ZONE 2 mo /62 FLA/V7 E4, 995* FRACTION/170R M0 /66 /64RETURN /46\. ///8 0 6A5 /44 42 2 //6 2 I30 /36 //3a //0 #4) f 7 f 2 f lFEED l 1/; M2 r GAS Mali/[477w M CONTACT Mum? /26 mvucra/a /34 Mum?PROCESS FOR OBTAINING DEUTERIUM FROM HYDROGEN-CONTAINING COMPONENTS ANDTHE PRODUCTION OF HEAVY WATER THEREFROM ral gas is transferred to ahydrogen stream having less than the normal concentration of deuteriumand thereafter recovering the deuterium from such hydrogen stream.

In addition to its utility as a tracer in biological and chemicalprocesses and other laboratory employments, the hydrogen isotope of mass2, designated as deuterium, has recognized nuclear properties favoringthe employment of deuterium in the form of deuterium oxide or heavywater (D 0) as a moderator for nuclear reactors. Deuterium is also afuture potential fuel for a fusion type nuclear reactor now underdevelopment. In the past, however, the art has been confronted with theproblem of producing deuterium or heavy water eco nomically insufficiently high concentrations and in adequate quantities. This is dueto the fact that the normal concentration of deuterium in hydrogen orhydrogen-containing materials is extremely low. Thus, moleculardeuterium occurs in natural hydrogen, water and other hydrogen-bearingcompounds in an average abundance in the range from about 0.010 to about0.016 mole percent relative to the molecular hydrogen content of thematerial. On the other hand, however, reactor-grade" heavy waterrequires a concentration above 99 percent D 0. While in the past varioustechniques have been suggested for the enrichment of the deuterium oxidecontent in water or the isolation or separation of deuterium fromhydrogen or hydrogencontaining materials, such processes have shownsevere shortcomings when it has been attempted to apply them to acommercial scale. Usually such processes require the treatment ofextremely large quantities of materials and/or have resulted inextremely high costs due to excessive equipment and power requirements,coupled with a low processing efficiency reflected in recoveries of onlyabout percent of the deuterium content of the stream. These previouslysuggested techniques have included electrolysis of water, vacuumdistillation of water and chemical exchange processes requiringdeuterium exchange from one hydrogen-containing compound to another,such as, for example, the H S/H O, li /H O and NI-l /H exchanges.

To illustrate the magnitude of the operation required, it has beenestimated that an inventory of about one ton of D 0 would be requiredfor each megawatt of electrical energy output from a nuclear power plantand that a plant in the range from about 300 to about 500 megawattswould be required for an economic operation while 1000 to 10,000megawatt plants have been projected. Similarly, it has been estimatedthat only about tons of D 0 per year might be produced from thedeuterium that could be separated from 50 tons of hydrogen per day.Assuming a normal operation of approximately 330 days per year, thesefigures would then indicate that 660 tons of hydrogen would have to betreated for each ton of D 0 produced and that to provide the inventoryof D 0 required for a 300 megawatt nuclear power plant would requireprocessing approximately 198,000 tons of hydrogen. To express it anotherway, it would require processing about 100,000,000 cubic feet per day ofpure hydrogen to obtain about tons per year of heavy water. Obviouslythen, techniques of this type would require the heavy water plant to beparasitic to hydrogen production facilities of almost astronomicalmagnitude.

Thus, while it is technically possible to obtain deuterium by separationof the natural abundance thereof from hydrogen by fractionation ordistillation, such technique is not feasible from a commercialstandpoint due to the fact that in a single plant operation theproduction in one location of the vast quantity of hydrogen requiredwould necessitate the employment of hydrogen production facilities of amagnitude that is impracticable, not to mention the size of thedeuterium separation facility that would also be required. Such anoperation would be well nigh impossible. On the other hand, theemployment of a multiplicity of comparatively smaller plants atdifferent locations, while being more compatible with presenttechnology, still presents an infeasible scheme since such would resultin obtaining portions of the desired product in diverse locations andstill require production of hydrogen in quantities far in excess ofcurrent demands for hydrogen in single locations. This would result insubstantial portions of the hydrogen production costs to be borne solelyby the deuterium separation operation, thereby making the cost ofdeuterium production prohibitive. Similarly, it should be noted that inmost existing commercial hydrogen plants, wherein the hydrogen isprimarily produced for utilization in other commercial processes and thecost of hydrogen production is therefore borne by such other processes,the quantity of hydrogen produced is insufi'lcient to provide asufficiently large quantity of deuterium to warrant recovery thereof.

Accordingly, the source of deuterium for any commercial operation mustbe material which is readily available in large quantities and availableat a minimal cost. Exemplary of such a material is water. In thisconnection, however, it is noted that in the U. S. Atomic EnergyCommission plant at Savannah River, wherein water is employed as thebasic source of deuterium, the required sequence of H S/H O transferfollowed by vacuum distillation and finally electrolytic processing toproduce D 0 of 99 percent plus purity still results in a product havinga subsidized market price of over $28 per pound.

Another material which is readily available in many areas of the worldin large quantities which also represents a good source of deuterium isnatural gas containing low molecular weight hydrocarbons such as, forexample, materials containing up to about six carbon atoms. Particularlyadvantageous as a source of deuterium is methane which contains fourhydrogen atoms per molecule as compared to the two hydrogen atoms permolecule of water. Thus, on a theoretical consideration methane shouldcontain approximately twice the amount of deuterium per molecule as doeswater. Attempting the upgrading of the deuterium content of methane viaa technique such as distillation again provides a technique which, whileapparently technically possible, is commercially infeasible due to thetremendous quantities of equipment and power needed to obtain a slightenhancement in dueterium content. Thus, while methane or natural gas canbe an inexpensive raw materiad for the production of deuterium or heavywater, the cost of processing by the techniques previously suggested bythe art have militated against any attempt to recover deuterium fromnatural gas or methane.

l have discovered a process whereby deuterium in high concentration canbe recovered from relatively hydrogen-rich source material through asimple, economic process requiring comparatively low capital investmentin equipment. Further, I have discovered that such deuterium can beconverted simply and efficiently into heavy water of greater than 99percent plus purity. The relatively hydrogen-rich source materialemployed as the charge stock in my invention can be any material inwhich the ratio of hydrogen atoms to all other atoms is at least 2:1 andpreferably in which the ratio is 3:1 or greater. Accordingly, the chargestock employed can be comprised of substantially a single compound, suchas, for example, methane, ammonia or an alcohol, or it can be comprisedof a mixture or blend of different compounds, such as, for example, anatural gas stream or a liquefied petroleum gas stream.

In accordance with my invention a deuteriumcontaining relativelyhydrogen-rich source material is contacted with hydrogen from which thedeuterium normally present therein has been removed or at leastsubstantially reduced. Preferably such hydrogen is substantiallydeuterium-free, i.e., hydrogen rather than the normal mixture ofhydrogen and HD having a deuterium concentration of about 0.0 l 5 molepercent deuterium (D This contacting is effected while in the presenceof and in contact with a hydrogenationdehydrogenation catalyst at anelevated temperature, e.g., greater than about 250 or 300 F., therebyeffecting a transfer of deuterium from the source material to thehydrogen, to produce a mixture of deuteriumenriched hydrogen (HD and Hand deuterium-lean source material. As employed in.the specification andclaims hereof, the term deuterium-enriched hydrogen" means hydrogen intowhich deuterium has been transferred thereby increasing the deuteriumcontent of the hydrogen to a level greater than that prior to thetransfer, regardless of whether the deuterium content of the enriched"hydrogen is even equal to, much less greater than, the normal abundanceof deuterium in hydrogen. Conversely, the term deuterium-lean" means amaterial, such as methane or other source material, from which deuteriumhas been transferred thereby decreasing the deuterium content of thematerial from the level of deuterium content prior to the transfer,regardless of whether the material initially contained a normalabundance of deuterium or had previously been subjected to a transferreaction for the removal of deuterium.

The mixture of deuterium-enriched hydrogen and dueterium-lean sourcematerial is removed from contact with the catalyst before cooling so asto prevent reversal of the equilibrium deuterium transfer reaction. Thedeuterium-enriched hydrogen is then separated from the deuterium-leansource material. This separated deuterium-enriched hydrogen is subjectedto a first fractionation, e.g., cryogenic fractional distillation, so asto provide a hydrogen fraction containing substantially less than thenormal concentration of deuterium and a fraction of super-enricheddeuterium content (substantially l-lD). The super-enriched deuteriumfraction is then contacted with a catalyst effective to equilibrate suchfraction so that the composition of the equilibrated fraction approachesthe equilibrium concentrations of 25 percent H 50 percent HD and 25percent D This equilibrated, super-enriched fraction is next subjectedto a second fractionation, e.g., cryogenic fractional distillation, toprovide a second deuterium-enriched hydrogen fraction (HD and H and ahigh-purity (99%+) deuterium fraction (D The high-purity deuteriumfraction is recovered and the second deuterium-enriched hydrogenfraction can be recycled to the first fractionation step.

The hydrogen fraction of reduced deuterium content, preferablydeuterium-free, obtained from the first fractionation step is thenrecycled to the contacting step to be contacted with thedeuterium-containing source material. Thus, the hydrogen of reduceddeuterium content, it will be seen, is produced in the operatingsequence of my invention. It will also be understood that thedeuterium-lean source material separated from the deuterium-richhydrogen stream in the separation step described above can be removedfrom the system and returned to storage or pipeline for laterutilization in any operation or processing wherein such material wouldnormally be employed.

The charge stock employed in my invention advantageously is a materialwhich is in the vapor phase at the operating conditions utilized duringcontacting with the hydrogen and catalyst. Thus, although any materialwhich is relatively rich in hydrogen and easily vaporized at operatingconditions is satisfactory, I prefer to employ light hydrocarbonscontaining up to about six carbon atoms. Particularly preferred chargestocks include methane, ethane and propane. It should also be pointedout that non-hydrocarbon materials relatively rich in hydrogen, e.g.,ammonia, are satisfactory charge stocks.

Advantageously, the charge stock employed in my invention is subjectedto a purification treatment prior to the initial contacting of chargestock and hydrogen. Such purification treatment is effective to removesome of the minor contaminants from charge stocks, such as, for example,the water, hydrogen sulfide, carbon dioxide, small quantities of heavyhydrocarbons, etc., which might be present in natural gas or entrainedin methane and which materials might have an adverse affect upon thecatalysts employed in my process or whose presence might be undesirablein cryogenic processing due to the fact that they might solidify at thelow temperatures required. This purification can be effected using anyof the various techniques well known in the art, such as, for example,by contacting the raw feed with an adsorbent material, e.g., charcoal,alumina, molecular sieves, etc., or by specialized low-temperatureseparations. Undesired contaminants can also be removed by absorptionwith an organic solvent, amine, methanol, sulfolane, etc.

In the step of contacting the deuterium-containing relativelyhydrogen-rich source material with the hydrogen of reduced deuteriumcontent the catalyst employed can be any of the well-knownhydrogenationdehydrogenation catalysts, including, for example, alumina,Group VI and Vlll metals and their oxides, either alone or supported oncarriers, such as alumina, and catalysts such as silica orsilica-alumina. I prefer, however, to employ alumina (particularlyhigh-purity alumina), and Group Vlll metals, specifically Group Vlllnoble metals, such as platinum and palladium and particularly platinum.

In effecting the contacting of the deuteriumcontaining source material,hydrogen of reduced deuterium content and catalyst, the temperatureemployed is an elevated temperature ranging from about a few hundreddegrees Fahrenheit above room temperature up to the thermal breakdowntemperature of the material being processed. Generally, the temperatureis maintained in the range from about 400 to about 1800 F. andpreferably in the range from about 600 to about 1500 F. More preferredtemperatures are in the range from about 800 to about 1200 F. Whencharging a hydrocarbon source material, the higher temperatures of theabove ranges are associated with the processing of lower molecularweight materials. The pressures utilized during such contacting canrange from atmospheric pressure up to about 10,000 psia and preferablyare maintained in a range from about 50 to about 5000 psia. Usually,however, the maximum pressure employed will not be greater than about3000 psia, with pressures lower than 1000 psia not only beingsatisfactory but pressures below about 500 psia being desirable.Advantageously, the pressure maintained during contacting is at leastabout 150 psia. This is particularly so when the deuterium-enrichedhydrogen is to be subjected to a cryogenic fractional distillation sinceit is desirable to operate the fractionator at a temperature near thecritical temperature of hydrogen which in turn requires a minimumpressure of about 125 psia at the top of the fractionator in order tomaintain a liquid phase in the bottom of the fractionator. Thus, apressure of 150 psia or greater in the contacting step makes allowancefor a pressure drop through the system and still provides a pressure ofI25 psia in the fractionator without requiring compression of thedeuteriumenriched hydrogen.

The feed rate of the charge stock, in the vapor phase, plusdeuterium-lean hydrogen is to be in the range from about 1000 to about100,000 standard volumes of gas per hour per volume of catalyst andpreferably is maintained in the range from about 4000 to about 50,000volumes of gas per hour per volume of catalyst. More preferred feedrates are in the range from about 6000 to about 20,000 standard volumesof gas per hour per volume of catalyst. In operating this contactingstep the volume ratio of hydrogen to charge gas is in the range fromabout 5:] to about 0.5:] and preferably from about 2:1 to about 121.

While it is important to maintain operating conditions during contactingwithin the above ranges so as not to hinder the deuterium transfer andto permit ready integration of the contacting step into the balance ofthe process scheme, the operating condition which has the greatesteffect upon the deuterium transfer effected during such contacting istemperature. This is due to the fact that the effectiveness of thedeuterium transfer is dependent upon equilibrium, which varies withtemperature. The remaining operating conditions employed duringcontacting have either a more limited or no effect upon the deuteriumtransfer.

After contacting of the hydrogen stream of reduced deuterium content,the deuterium-containing charge gas and the catalyst to provide adeuterium-enriched hydrogen stream and a deuterium-lean gaseous sourcematerial stream, the resultant hydrogen and source material mixture isremoved from contact with the catalyst before permitting any reductionin temperature of the mixture. The hydrogen stream is then separatedfrom the gaseous source material stream. This can be accomplished quitereadily by various techniques known to the art such as, for example,contacting a hydrogen and hydrocarbon stream with a bed of selectivelyadsorbent material, as well as by low temperature (cryogenic)fractionation or low temperature flashing. These latter methods arequite suitable for the separation of hydrogen and hydrocarbon due to thesubstantial differences in boiling points of hydrogen and hydrocarbons(BP: H about 253C.; CH. about l62C.).

In the fractionation of the deuterium-enriched hydrogen stream acryogenic fractional distillation can be employed and a separation ofthe hydrogen from its other isotopes effected readily due to thedifferences in vapor pressure existing between such isotopes. In thisfirst fractionation of my invention I effect a separation substantiallybetween hydrogen on the one hand and HB on the other hand. While,advantageously, such separation will permit removal of substantiallypure hydrogen overhead, such an exact separation is not essential and ahydrogen stream which has been stripped so that is contains up to about30 to 50 ppm l-ID has been found to be satisfactory. Preferably,however, the separated hydrogen contains no more than about 10 ppm HD.This low concentration of HD in the separated hydrogen or hydrogen ofreduced deuterium content advantageously provides an additional drivingforce in the desired direction of transfer based upon equilibriumconsiderations.

The superenriched deuterium fraction from which the substantiallydeuterium-free hydrogen has been separated will usually consist of aboutpercent HD with the balance being a certain amount of hydrogen as wellas some D The temperatures employed in the cryogenic fractionation toseparate the substantially deuterium-free hydrogen from thesuperenriched HD fraction are generally in the range from about 430 F.

up to about 400F. The pressure employed can be any.

pressure which, at the particular temperature being employed, willpermit formation, and thus separation, of the desired superenricheddeuterium liquid phase and the substantially deuterium-free hydrogenvapor phase. Such pressure includes both subatmospheric andsuperatmospheric pressures. Usually, however, I prefer to employpressures in the range from about psia up to about 500 psia.

Inasmuch as H l-ID and D tend not to achieve a favorable equilibrium atsuch extremely low temperatures, the superenriched deuterium from thefirst fractionation step is then brought to a higher temperature,usually about room temperature or above, e.g., up to about 300 F., andcontacted with a catalyst effective to equilibrate the substantially HDstream at such temperature. Suitable catalytic materials include, forexample, iron hydroxide, iron synthetic ammonia catalyst, alumina,platinum, iron, nickel or supported metal catalysts including platinum,iron, nickel, etc. supported on carriers such as alumina or kieselguhr.The result of such equilibration is to convert the stream which issubstantially HD into a form more closely approaching normal equilibriumof the various isotopes such that the equilibrated stream is composedsubstantially of 25 percent H 50 percent HD and 25 percent D Thisequilibrated stream is then cooled and subjected to a second cryogenicfractional distillation and this time is cut so as to separate as anoverhead fraction the hydrogen and HD components from the remaining Dcomponents. This fractionation provides a substantially pure D streamcomposed of 99%+ D e.g., 99.9 percent.

The temperature employed in this second cryogenic fractionation is inabout the same range as employed in the first cryogenic fractionationmentioned above. Similarly, the pressure employed is within the samerange as for the first cryogenic fractionation. I prefer, however, toemploy a temperature in the second cryogenic fractionation which ishigher than employed in the first fractionation, albeit only slightlyhigher. Usually, the temperature of the second fractionation ismaintained about 2 or 3 higher than the temperature employed in thefirst fractionation. 1 also prefer to employ a pressure in the secondfractionation which is about 20 to 30 psi greater than the pressureemployed in the first fractionation.

In order to define my invention in greater detail, reference is made tothe drawings wherein:

FIG. 1 is a schematic flow diagram of the basic process of my invention;and

FIG. 2 is a schematic flow diagram ofa preferred embodiment of myinvention.

It will be understood that these drawings have been greatly simplifiedso that various pumps, compressors, heat exchange means, and the like,have not been shown for the sake of simplicity.

Referring now to HO. 1, the feed gas, such as natural gas or methane,with its normal abundance of deuterium, is passed by means ofline andintroduced into contactor 12 wherein is located a bed of ahydrogenation-dehydrogenation catalyst such as, for example, alumina,platinum or platinum on alumina. Substantially deuterium-free hydrogenobtained by stripping deuterium from hydrogen elsewhere in the processis also introduced into contactor 12 by means of line 14. A temperaturein the range from about 500 to about 1600 F., preferably above 700 F.,is maintained in contactor 12. The pressure in contactor 12 ismaintained at a level below about 400 psia, and preferably below about300 psia but above about 100 psia. The result of this contacting incontactor 12 is to transfer the deuterium from the feed gas of line 10to the hydrogen stream ofline 14. While maintaining this elevatedtemperature, a combined effluent stream is removed from contactor 12 bymean ofline 16, and thereafter cooled and passed to hydrogen separator18.

In hydrogen separator 18 the combined stream is further reduced intemperature so as to effect a separation of hydrogen and its isotopesfrom the feed gas, e.g., methane or natural gas. The separated feed gasis taken from separator 18 by means of line 20 and removed from thesystem. The stream of hydrocarbon gas of line 20 can be returned to thesource of the feed gas, e.g., storage or pipeline, or can be utilized inother processes.

The stream of hydrogen and its isotopes, now in the form of a combinedhydrogen and HD stream is removed from separator 18 by means of line 22and passed to fractionator 24 wherein the combined H HD stream issubjected to cryogenic fractional distillation. This fractionation isconducted so as to provide a substantially complete separation ofhydrogen from deuterium-containing molecules resulting in the productionof a substantially deuterium-free hydrogen fraction which is removedoverhead by means of line 14 and recycled to contactor 12 describedpreviously. The remaining fraction comprising substantially HD is thenremoved from fractionator 24 by means of line 26 and passed toequilibration reactor 28.

As mentioned previously, the various isotopes of hydrogen tend not toachieve a favorable equilibrium at the low temperatures existing infractionator 24 and required for the cryogenic fractional distillation.Accordingly, the substantially HD stream ofline 26 is warmed andcontacted with a catalyst effective to cause equilibration of thevarious hydrogen isotopes at temperatures such as, for example, roomtemperature up to about 300 F. The contacting of the HD stream of line26 with the equilibration catalyst in reactor 28 results in theproduction of an isotopic mixture approximating the equilibriumdistribution of about 25 percent H 50 percent HD and 25 percent D Thisequilibrated stream is then removed from reactor 28 by means of line 30,cooled and passed to a second fractionator 32.

In fractionator 32 the equilibrated stream of line 30 is subjected to acryogenic distillation quite similar to that employed in fractionator 24but operated at a slightly higher temperature and preferably at aslightly higher pressure so as to effect a split between a combined Hand HD fraction and a substantially pure D fraction. The l-l -HDfraction is removed overhead from fractionator 32 by means of line 34and recycled to fractionator 24. The substantially pure, e.g., 99%+ Dfraction is removed from fractionator 32 by means of line 36. Thissubstantially pure deuterium fraction of line 36 can then be recoveredas product.

Additionally, the deuterium fraction of line 36 can be further processedby passing it to a combustion zone 38 wherein it can be combined with asubstantially pure oxygen stream introduced by means of line 40 andburned so as to produce heavy water (D 0) after which the heavy watercan be removed by means of line 42 and recovered as reactor-grade heavywater.

Advantageously, the raw feed gas of line 10 can be subjected topurification by a cryogenic system or by contacting with an adsorbentmaterial effective to remove contaminants, such as water, carbonmonoxide, etc. As illustrated in FIG. 1, the feed gas of line 10 isshown being conducted through a purification zone 44 prior tointroduction of the feed gas to contactor 12.

Referring now to FIG. 2 of the drawings which shows a schematic flowdiagram of a preferred embodiment of my invention, such flow scheme willbe described in conjunction with the following example.

EXAMPLE A feed gas stream comprising substantially raw methane with itsnormal abundance of deuterated methane (Cl-1 D, the normally occurringmaterial, assumed to be present in a concentration of approximately 0.06mol percent) and flowing at the rate of about 400 million standard cubicfeet per day (400 MM SCFD) is passed by means of line into apurification unit 112 containing a bed of molecular sieves. Thiscontacting is effective to remove any contaminants from the methanestream which might have an adverse effect on either catalysts or lowtemperature operating steps employed subsequently. The purified methanestream is now passed by means of line 114 to a first contactor 116. Arecycle stream of hydrogen containing less than a normal abundance ofdeuterium and flowing by means of line 138 at the rate of about 800 MMSCFD is combined with a hydrogen stream of line 1 18 flowing at the rateof about 0.2 MM SCFD (as make-up to' replace D and H removed from thesystem) and the methane stream of line 114 prior to its introductioninto contactor 116. The ratio of hydrogen to methane is maintained atabout a 2:1 volume ratio In contactor 116 the combined hydrogen andmethane stream is contacted with a high-purity alumina catalyst at atemperature of about 800 to 1200 F., at a pressure of about 130 to 150psia and at a space velocity of about 20,000 volumes of methane plushydrogen per volume of catalyst per hour. This contacting is effectiveto provide a transfer of a substantial quantity of the deuteriuminitially present in the raw methane stream to the hydrogen streaminitially containing less than the normal abundance of deuterium, sincethe combined methane and hydrogen stream tend to reach an equilibriumdistribution of deuterium between the two materials and since thehydrogen stream initially contained less than its normal abundance ofdeuterium. The deuterium transferred to this hydrogen stream isgenerally in the form of HD.

Subsequent to the transfer reaction occurring in contactor 116 thecombined effluent stream flowing at the rate of about 1200 MM SCFD isremoved therefrom by means ofline 120, cooled and passed to hydrogenseparator 122. In separator 122 a low-temperature separation is readilyeffected at a temperature of about "300 F. and a pressure of about 130psia so as to separate hydrogen and its isotopes from methane therebyproviding a methane stream containing a reduced quantity of deuteriumand a combined H -HD stream. The H HD stream is removed from separator122 by means ofline 124 at a rate of about 800 MM SCFD and passed tocryogenic fractionator 126, while the methane stream is removed fromseparator 122 at a rate of about 400 MM SCFD and passed by means of line128 to a second contactor 130.

The H -HD stream of line 124 is subjected to a cryogenic fractionationin fractionator 126 so as to effect substantially a separation betweenthe H and the HD components of such stream. The maintenance ofatemperature in fractionator 126 of about 400 F. and a pressure of 125psia is effective to provide an overhead H stream containing no morethan about ppm HD. Similarly, the employment of such conditions iseffective to provide a fractionator bottoms stream of about 95 percentHD. The hydrogen fraction containing less than 10 ppm HD is then removedoverhead from fractionator 126 by means of line 132 at a rate of about800 MM SCFD and combined with the methane stream of line 128 prior tointroduction into contactor 130.

The combined streams oflines 128 and 132 are contacted with a catalystof high-purity alumina at a temperature of about 800 to 1200 F. and apressure of about 130 to 150 psia in contactor 130. Again, the ratio ofthe hydrogen stream of line 132 to the methane stream of line 128 ismaintained at about 2:1 and a space velocity of about 20,000 volumes ofmethane plus hydrogen per volume of catalyst per hour is also maintainedin contactor 130. This contacting is effective to provide a furthertransfer of deuterium from the methane into a hydrogen stream initiallycontaining less than the normal abundance of deuterium. The combinedeffluent stream from contactor flowing at the rate of about 1200 MM SCFDis then passed by means of line 134 into hydrogen separator 136maintained at a temperature of about 300 F. and a pressure of about 120psia whereby a hydrogen stream of enriched deuterium content butgenerally containing less than normal abundance of deuterium isseparated from the now deuterium-lean methane by means of a lowtemperature separation. The separated hydrogen is removed from separator136 by means of line 138 at a rate ofabout 800 MM SCFD and is thencombined with the purified raw methane stream of line 114 and thehydrogen stream of line 118 prior to introduction into contactor 116.

The deuterium-lean methane stream separated in separator 136 is removedtherefrom by means of line 140 and recycled to purification unit 112where it is employed to purge the molecular sieve beds. Thisdeuterium-lean methane stream is removed from purification unit 112 bymeans ofline 142 at a rate of about 400 MM SCFD and is returned to thesource of the feed gas by means of line 144. When the stream of line 140is not required for the purging of the molecular sieve beds, it need notbe passed through purification unit 112 but can be returned directly tothe source of feed gas, by means not shown. A minor portion of thedeuterium-lean methane stream ofline 140 is passed by means of line 146to a hydrogen plant 148, such as a stream reforming plant, in order toprovide the small quantity of makeup hydrogen required in thisembodiment of my invention. It will be understood that since the methanestream charged to the hydrogen plant 148 is substantially deuterium-freemethane, the hydrogen produced in hydrogen plant 148 and introduced intothe reaction system by means of line 118 will also be substantiallydeuterium-free.

The HD bottoms fraction from fractionator 126 is removed therefrom bymeans of line 150 at a rate of about 0.4 MM SCFD and passed toequilibrium reactor 152 wherein the HD stream is contacted with an ironhydroxide catalyst at a temperature of about 250 F. and a pressure ofabout 200 psia thereby effecting an equilibration of the varioushydrogen isotopes in order to provide a substantially equilibriummixture of isotopic components approaching the equilibrium distributionof 25 percent H 50 percent HD and 25 percent D This equilibrated streamis then removed from reactor 152 by means of line 154, cooled and passedto fractionator 156 wherein this stream is subjected to a cryogenicfractionation.

Fractionator 156 is operated in substantially the same manner asfractionator 126 employing a temperature of about 400 F. and a pressureof about 150 psia except that in fractionator 156 a slightly highertemperature is used in order to effect a separation into a combined H-HD fraction and a substantially pure D fraction. The H -HD fraction isremoved overhead from fractionator 156 by means of line 158 at a rate ofabout 0.3 MM SCFD and recycled to fractionator 126 thereby providing forthe further separation of the H from the HD component in the stream ofline 158.

The substantially pure D fraction is removed from fractionator 156 bymeans of line 160 at a rate of about 80,000 SCFD and passed to acombustion zone 162 wherein it is combined with substantially pureoxygen (99%+) also introduced into combustion zone 162 by means of line164. The result of this combustion of the substantially pure deuteriumstream with substantially pure oxygen is the production of reactor-gradeheavy water comprising 99%+ D which is removed from combustion zone 162by means of line 166 at the rate of about 2.1 short tons per day.

In this operation the amount of makeup hydrogen added to the system,such as from hydrogen plant 148 via line 118, is sufficient tocompensate for the quantity of deuterium removed from the system as Dsuch as via line 160, or as D 0, such as via line 166, together with thesmall quantity of hydrogen dissolved or entrained in the return gas andthus removed from the system, such as via line 144.

I claim:

1. A process for transferring deuterium from a deuterium-containingrelatively hydrogen-rich hydrocarbon source material which is in thevapor phase at the operating conditions utilized during contacting withhydrogen and in which the ratio of hydrogen atoms to all other atoms isat least 2:1, which process comprises contacting the source materialwith hydrogen of reduced deuterium content and ahydrogenationdehydrogenation catalyst at a temperature in the range fromabout 400 to about 1800 F., a pressure from about atmospheric up toabout 10,000 psia and a feed rate of hydrogen-rich source material, inthe vapor phase, plus hydrogen from about 1,000 to about 100,000standard volumes of gas per hour per volume of catalyst with the volumeratio of hydrogen to source material being from about 5:1 to about0.521, thereby producing deuterium enriched hydrogen and source materialof reduced deuterium content, separating the deuterium-enriched hydrogenfrom the source material of reduced deuterium content, and thenrecovering the deuterium-enriched hydrogen.

2. A process for recovering deuterium from a deuterium-containingrelatively hydrogen-rich hydrocarbon source material which is in thevapor phase at the operating conditions utilized during contacting withhydrogen and in which the ratio of hydrogen atoms to all other atoms isat least 2: 1, which process comprises 1. transferring deuterium fromthe source material to hydrogen of reduced deuterium content bycontacting the source material and hydrogen of reduced deuterium contentwith a hydrogenationdehydrogenation catalyst at a temperature in therange from about 400 to about 1800F., a pressure from about atmosphericup to about 10,000 psia and a feed rate of hydrogen-rich sourcematerial, in the vapor phase, plus hydrogen from about 1,000 to about100,000 standard volumes of gas per hour per volume of catalyst with thevolume ratio of hydrogen to source material being from about 5:1 toabout 0.5:1, thereby producing deuterium-enriched hydrogen and sourcematerial of reduced deuterium content,

2. separating the deuterium-enriched hydrogen from the source materialof reduced deuterium content,

3. subjecting the deuterium-enriched hydrogen to a first fractionationto provide a superenriched deuterium fraction and a hydrogen fraction ofreduced deuterium content,

4. contacting the superenriched deuterium fraction with a catalysteffective to equilibrate the superenriched deuterium fraction at atemperature from about room temperature up to about 300F.,

5. subjecting the equilibrated, superenriched deuterium fraction to asecond fractionation to provide a deuterium-enriched hydrogen fractionand a substantially pure deuterium fraction, and

6. recovering the substantially pure deuterium fraction from step 5 asproduct.

3. The process of claim 2 wherein the deuteriumenriched hydrogenfraction from step (5) is recycled to the first fractionation of step(3).

4. The process of claim 2 wherein the hydrogen fraction of reduceddeuterium content from step (3) is recycled to the contacting of step(1).

5. The process of claim 2 wherein the hydrogen of reduced deuteriumcontent is substantially deuteriumfree.

6. The process of claim 2 wherein the source material is natural gas.

7. The process of claim 2 wherein the source material is a lower boilinghydrocarbon containing less than about six carbon atoms.

8. The process of claim 2 wherein the source material is methane.

9. The process of claim 2 wherein the source material is subjected to apurification treatment prior to the contacting of step (1).

10. A process for obtaining deuterium from a stream of deuteriumcontaining hydrogen-rich hydrocarbon source material which is in thevapor phase at the operating conditions utilized during contacting withhydrogen and in which the ratio of hydrogen atoms to all other atoms isat least 2:1, which process comprises 1. purifying thedeuterium-containing source material so as to remove contaminantstherefrom,

2. contacting the purified source material stream with a stream ofhydrogen containing less than a normal abundance of deuterium and ahydrogenation-dehydrogenation catalyst at a temperature from about 400to about 1800F., a pressure from about atmospheric up to about 10,000psia and a feed rate of source material, in the vapor phase, plushydrogen from about 1,000 to about 100,000 standard volumes of gas perhour per volume of catalyst with the volume ratio of hydrogen to sourcematerial being from about 5:1 to about 05:1 in a first transfer stagethereby transferring deuterium from the source material stream to thehydrogen stream and producing a first deuteriumenriched hydrogen streamand a first source material stream of reduced deuterium content,

3. separating the first deuterium-enriched hydrogen stream from thefirst source material stream of reduced deuterium content,

4. fractionating the first deuterium-enriched hydrogen stream into asubstantially deuterium-free hydrogen fraction and a superenricheddeuterium fraction,

5. combining the first source material stream of reduced deuteriumcontent from step (3) and the substantially deuterium-free hydrogenfraction from step (4),

6. passing such combined stream into contact with ahydrogenation-dehydrogenation catalyst at a temperature from about 400to about 1800F., a pressure from about atmospheric up to about 10,000psia and a feed rate of source material, in the vapor phase, plushydrogen from about 1,000 to about 100,000 standard volumes of gas perhour per volume of catalyst with the volume ratio of hydrogen to sourcematerial being from about :1 to about 0.5: l in a second transfer stagethereby producing a second hydrogen stream of enriched deuterium contentbut containing less than a normal abundance of deuterium and a secondsource material stream of further reduced deuterium content,

7. separating the second hydrogen stream of enriched deuterium contentfrom the second source material stream of further reduced deuteriumcontent,

8. passing the second hydrogen stream containing less than a normalabundance of deuterium from step (7) to the first transfer stage of step(2),

9. contacting the superenriched deuterium fraction from step (4) with acatalyst effective to equilibrate such fraction at a temperature fromabout room temperature up to about 300F.

l0. subjecting the equilibrated, superenriched deuterium fraction to asecond fractionation to provide a deuterium-enriched hydrogen fractionand a substantially pure deuterium fraction, and

l 1. recycling the deuterium-enriched hydrogen fraction to the firstfractionation step and recovering the substantially pure deuteriumfraction as product.

11. The process of claim 10 wherein the source material is natural gas.

12. The process ofclaim 10 wherein the source material is methane.

13. A process for producing heavy water of high concentration whichcomprises reacting the substantially pure deuterium product from claim 2with substantially pure oxygen thereby producing substantially pureheavy water (D 0).

14. A process for producing heavy water of high concentration whichcomprises reacting the substantially pure deuterium product from claim10 with substantially pure oxygen thereby producing substantially pureheavy water (D 0).

2. A process for recovering deuterium from a deuterium-containingrelatively hydrogen-rich hydro-carbon source material which is in thevapor phase at the operating conditions utilized during contacting withhydrogen and in which the ratio of hydrogen atoms to all other atoms isat least 2:1, which process comprises
 2. contacting the purified sourcematerial stream with a stream of hydrogen containing less than a normalabundance of deuterium and a hydrogenation-dehydrogenation catalyst at atemperature from about 400* to about 1800*F., a pressure from aboutatmospheric up to about 10,000 psia and a feed rate of source material,in the vapor phase, plus hydrogen from about 1,000 to about 100,000standard volumes of gas per hour per volume of catalyst with the volumeratio of hydrogen to source material being from about 5:1 to about 0.5:1in a first transfer stage thereby transferring deuterium from the sourcematerial stream to the hydrogen stream and producing a firstdeuterium-enriched hydrogen stream and a first source material stream ofreduced deuterium content,
 2. separating the deuterium-enriched hydrogenfrom the source material of reduced deuterium content,
 3. separating thefirst deuterium-enriched hydrogen stream from the first source materialstream of reduced deuterium content,
 3. subjecting thedeuterium-enriched hydrogen to a first fractionation to provide asuperenriched deuterium fraction and a hydrogen fraction of reduceddeuterium content,
 3. The process of claim 2 wherein thedeuterium-enriched hydrogen fraction from step (5) is recycled to thefirst fractionation of step (3).
 4. The process of claim 2 wherein thehydrogen fraction of reduced deuterium content from step (3) is recycledto the contacting of step (1).
 4. fractionating the firstdeuterium-enriched hydrogen stream into a substantially deuterium-freehydrogen fraction and a superenriched deuterium fraction,
 4. contactingthe superenriched deuterium fraction with a catalyst effective toequilibrate the superenriched deuterium fraction at a temperature fromabout room temperature up to about 300*F.,
 5. subjecting theequilibrated, superenriched deuterium fraction to a second fractionationto provide a deuterium-enriched hydrogen fraction and a substantiallypure deuterium fraction, and
 5. combining the first source materialstream of reduced deuterium content from step (3) and the substantiallydeuterium-free hydrogen fraction from step (4),
 5. The process of claim2 wherein the hydrogen of reduced deuterium content is substantiallydeuterium-free.
 6. The process of claim 2 wherein the source material isnatural gas.
 6. passing such combined stream into contact with ahydrogenation-dehydrogenation catalyst at a temperature from about 400*to about 1800*F., a pressure from about atmospheric up to about 10,000psia and a feed rate of source material, in the vapor phase, plushydrogen from about 1,000 to about 100, 000 standard volumes of gas perhour per volume of catalyst with the volume ratio of hydrogen to sourcematerial being from about 5:1 to about 0.5:1, in a second transfer stagethereby producing a second hydrogen stream of enriched deuterium contentbut containing less than a normal abundance of deuterium and a secondsource material stream of further reduced deuterium content, 6.recovering the substantially pure deuterium fraction from step 5 asproduct.
 7. separating the second hydrogen stream of enriched deuteriumcontent from the second source material stream of further reduceddeuterium content,
 7. The process of claim 2 wherein the source materialis a lower boiling hydrocarbon containing less than about six carbonatoms.
 8. The process of claim 2 wherein the source material is methane.8. passing the second hydrogen stream containing less than a normalabundance of deuterium from step (7) to the first transfer stage of step(2),
 9. contacting the superenriched deuterium fraction from step (4)with a catalyst effective to equilibrate such fraction at a temperaturefrom about room temperature up to about 300*F.
 9. The process of claim 2wherein the source material is subjected to a purification treatmentprior to the contacting of step (1).
 10. A process for obtainingdeuterium from a stream of deuterium containing hydrogen-richhydrocarbon source material which is in the vapor phase at the operatingconditions utilized during contacting with hydrogen and in which theratio of hydrogen atoms to all other atoms is at least 2:1, whichprocess comprises
 10. subjecting the equilibrated, superenricheddeuterium fraction to a second fractionation to provide adeuterium-enriched hydrogen fraction and a substantially pure deuteriumfraction, and
 11. recycling the deuterium-enriched hydrogen fraction tothe first fractionation step and recovering the substantially puredeuterium fraction as product.
 11. The process of claim 10 wherein thesource material is natural gas.
 12. The process of claim 10 wherein thesource material is methane.
 13. A process for producing heavy water ofhigh concentration which comprises reacting the substantially puredeuterium product from claim 2 with substantially pure oxygen therebyproducing substantially pure heavy water (D2O).
 14. A process forproducing heavy water of high concentration which comprises reacting thesubstantially pure deuterium product from claim 10 with substantiallypure oxygen thereby producing substantially pure heavy water (D2O).